In this scenario, you only have to cheat a little bit. It won't be long before the Assyrians will hit you with invasions of 10 units at a time. You will need a continuous wall around your entire city and lots of troops. The instructions hint at this. Bear in mind as well that, when the AI is attacking, it cheats - it can see all of your units and buildings without needing any scouts.
Gathering your resources
You start out with 6 villagers, which is actually quite a lot, but you don't know where you will find wood, and you don't know whether you will find gold. Accordingly, your first priority is to produce a Scout, which allows you to produce two more villagers right away. Put four villagers on food and two on stone, and look for a good place to build a Stable with the next two. While doing this, you find a small forest. Building an early fleet is not an option, because you still don't have the wood to support it.
Work up to 10 villagers, then save the rest of your food for troops. You will produce a few more villagers after you have a substantial army. In the meantime, explore your continent. You quickly find that you will have at least 1200 stone. You find 8 gold mines close by, which is enough to get you a substantial Iron Age army. The east corner of the map is empty, which means that that is a protected flank. The Chaldeans are close by and very weak on the ground, so you should be able to wipe them out easily, except for their fleet. So far, this is all good news. The bad news is that your starting position is too close to the shore, and badly exposed. Furthermore, by the time that you will be able to afford a fleet, you will be far behind the Assyrians in that area, so you will need to prepare for it first, and you will need to defend against a lot of invasions in the meantime. The important thing is to not get so involved in taking out the Chaldeans that you forget to build defenses or pump the economy. Building defenses takes a lot of micromanagement, and so does efficient attacking, and so does hunting, and you simply cannot do it all at once. It is probably best to avoid hunting entirely until much later, and to attack the Chaldeans only to cripple their economy, quickly pulling your attack force back inside your base.
Defending your walled fort against Assyrian invaders
You will find out quite soon that the Assyrians will attack you constantly, using a lot of cavalry. They arrive in groups of about 10 at a time, and each new wave arrives just as soon as the Transports make the return trip from their base. If you don't have a continuous wall by the time the first attack wave arrives, you will find out to your regret that they just sweep right by your military units and head straight for your weakest units. You need to know that the attacks will do that, otherwise you won't start building the wall early enough. You can't afford to have more than one opening in your wall, and it should face the Chaldeans.
The wall that you will need should seal off the entire east map corner, and loop around all of your buildings. This will take require about 350 stone. You will need the Bronze Age Tower and wall upgrades, which cost 150 stone. You can really only afford 2 Towers for 300 stone, which leaves 250 for repairs. Two of the Towers should be near the opening in your wall. Also make sure to have enough stone to upgrade your watch towers and walls.
The opening in your wall should be two spaces wide. If it is smaller, you will not be able to move through it properly. In order to stop the enemy cavalry from just running through it, you need to physically block it with two good melee units. However, you need to keep the opening open at all times except when the enemy is trying to rush through, otherwise they will attack the wall anywhere they like, and you don't want that. Cavalry will do as blockers to start, but once you figure out that the Assyrians are using a lot of cavalry, you should produce a couple of heavy infantry units to do that job.
Produce two Cavalry units right away, and 5 chariot archers as soon as you find the Chaldeans. You will get more Cavalry shortly, but you don't have the necessary gold yet, and you may need 2 priests first. It's a good idea to build one Tower in that area before you start attacking the Chaldeans. They have no more than 10 Axemen and a bunch of villagers, and two Cavalry plus 5 archers plus one Tower is quite enough to cripple them, although you will need healing at the end. One way of bringing their villagers out to play is to attack their buildings, but your actual objective is to kill all their villagers. When all the Chaldean villagers are dead, as best as you can determine, immediately retreat your troops back into your base. You don't have time to blow up any of the Chaldeans' buildings, including their Town Centre or their two Towers. The Chaldeans still have at least one fishing boat, i.e. a food income, so they will be able to rebuild their villagers. You will need to keep an eye on this in the Achievements section, and raid them again later as appropriate.
Watch out for the Chaldean villagers if they cut your trees, shoot them down with chariot archers and take out their storage pit if possible, you can also use 2 priest to convert the enemy cavalry to attack the invaders outside your wall.
Hopefully, all your troops will be back inside your base, and your wall complete, before the first Assyrian attack wave arrives. If so, block the opening in the wall with your Cavalry, and you should be fine. You will need to unblock the opening immediately after each attack, and for about 80% of the game, you will be shuffling your troops around in the wall opening and healing them and otherwise beating off continuous attacks. This will occupy your entire attention, and clearly, you will have no time to spare for hunting.
When your forage bushes are exhausted, build a Granary in the large open area in the corner of the map and farm. Get all the stone in as soon as you can, and you will need a lot of wood and food, but gold is a fairly low priority. Your primary combat force for most of the game will be two Hoplites, 5 Cavalry, one Scout, 5 archers, 5 chariot archers, and 2-4 priests. You will also have about 12 villagers. Don't bother getting more, because you will find that you don't have any work for them. The force described here is quite sufficient for defensive purposes, but no force that you could conceivably have would be enough to let you push out of your base. Accordingly, you are going to have to beat off attack after attack after attack and just wait for the Assyrians to run out of resources.
Invading the Chaldeans and Assyrians homeland
You will find that wood is actually in short supply. You do not have enough stone to build a really complete wall, so you will need to rely upon two forests to supplement your wall. Harvesting wood from those forests is very dangerous, because your villagers will cut openings in them unless you micromanage them carefully, and you can't, because you are too busy micromanaging the combat. Therefore your wood supply will dry up before too long, and for a long time, you will only be bringing in food, a bit of wood, and a bit of gold.
You can build a dock in the southeast corner which you can use to build fishing boats for food and trade boats to trade at the Assyrian dock for extra gold which is badly needed in this game for your priests, catapults and horse archers,
Also you can convert the enemy ships with 2 priests so you can take over the sea and get the upper hand in the game.
The Assyrian attacks do not use the best-quality units. They never use priests, and only a few catapults. In fact, the Assyrians are restricted to the Bronze Age. Eventually, you enter the Iron Age, after which you should produce 5 horse archers. Not long afterwards, the Assyrian attacks seem to get weaker. They also start using War Galleys, which could mean that their gold supply has dried up. Now you can start pushing out of your base and finishing off the Chaldeans. You might even be able to sink a few Assyrian Transports on the way in.
Don't blow up any of the Chaldeans' buildings that you can use. In particular, leave their dock, Storage Pits, and Granaries alone. You will convert these buildings later using priests.
Eventually, the time will seem right to seize the initiative. Rush a priest over to the Chaldean dock and convert it. Quickly produce 5 War Galleys. Locate and wipe out the Assyrian dock, and then explore their shore to make sure that there is no second dock. Now your continent is completely safe. Convert all the Chaldean depots and suck in all those beautiful resources. You now have a large surplus of all types of resource, because really, you don't need them anymore.
Produce a couple of Transports, or maybe you can convert the Chaldean ones. Produce a couple of catapults. All you need to finish off the Assyrians at this point is about 10 units (the proper ones, of course) on their continent.